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Transcript
ENGLISH-JAPANESE TRANSLATION THROUGH CASE-STRUCTURE CONVERSION
Fujio Nishida, Shinobu Takamatsu and Hiroaki Kuroki
Department of Electrical Engineering,
Faculty of Engineering, University of Osaka Prefecture,
Sakai, Osaka, 591 JAPAN
This paper reports some trials on mechanical
translation from English to Japanese through a
case structure constructed on Hornby~s verb patterns. Though the general theoryof case structures
is still at the beginning of study, it provides
partial sentential patterns with rough but resonable classification labels. After determination
of schematic dependency relations, multi-vocal
problems for choosing appropriate equivalents are
dissolved using subcategories of terms and cases.
Case structures of English are transformed into
those of Japanese if necessary, and from those ,
Japanese sentences are generated by a Japanese
grammar.
i. Introduction
parameters.
2. Case structures
2.1 Case structures of verbs
Many English words have multi-syntactic and semantic categories. However, these multi-categories
of a word in a sentence should be able to be dis
-solved in a context of the sentence, namely, in
syntactic and semantic relations to the neighboring words. A.S.Hornby has given comparatively
precise verb patterns. 3The use of verb patterns
at parsing is fairly effective to identify the
syntactic categories of words and phrases as well
as their syntactic roles such as complements and
adverbial infinitives.
On the other hand, an efficient introduction
of semantic information about words is very important in order to identify their semantic roles
and appropriate Japanese equivalents as well as
to dissolve the still remaining syntactic ambiguities after a syntactic analysis. For this
purpose, there are several approaches based on
the case grammar. 4 It is still in an incomplete
state for general purpose of thorough comprehension of sentences. But if it is used on detailed syntactic rules of the conventional word
usage with the aids of categories of an appropriate level at various stages of mechanical translation, these approaches based on the case grammar will serve fairly well to assign reasonable
English and Japanese are fairly different
languages from each other. Accordingly, it will
be necessary to make translation based on a kind
of deep structures of sentences which determines
sentential forms schematically in respective languages. The case structure used here is a conventional one which is closely related to surface
structures. But it was found that the case structure is fairly useful by adding some new means
in construction and usage of it.
The parsing for obtaining the case structure
from English sentences is done by category-matching on a fairly precise verb pattern given by A.S.
Hornby. It dissolves most of multi-syntactic and
semantic category problems of words and
phrases, and determines global dependency
F EXIStence
relations among constituents of English
•
~ ATTRibute
PHYSlcal-~POSSession
sentences.
-STate ~ S T a t e
I RELatio n
Subsequently, it determines the appL MENTal ~ P E R C E P t u a l STate
ropriate Japanese equivalents and postL STate
-]-EMOTive STate
positions among several candidates by
NATURal phenomenon
-EVENT
using subcategories of terms and individual prepositional words.
F Physical TRANSfer
The case structure thus obtained conP H Y S i c a l ~ P O S S e s s i v e TRANSfer
taines the modal part which represents
-~ATTRibute TRANSfer
A C T i o n ~ ACTi°n
various characteristics of the predicate
~ B O D i l y ACTion
part in almost independent form of respeTHINGS
a-PRODuction
ctive languages. It also embeds idiomaMental TRANSfer
L MENTal
tic expressions in itself.
PERCEPtual ACTion
ACTion
EMOTive ACTion
At the level of the case structure,
THINKing ACTion
the difference between both language
expressions is not so large. TransforLIVING object ~ H U M a n
mations of sentential forms such as those
r~ical~
<ANIMal
|
c~ [NON,LIVING
rNATURE
of non-livlng subjects and those of prinOBJECT ~
object
-~PRODUCTS
cipal clauses followed by long subordlMENTal OBJect
nate ones for readability are processed
MENTal SUBJect
at this stage without difficulty. From
the case structures transformed into
Japanese, translated sentences are geneFig.l The upper part of the categorical trees.
rated under control of various involved
~
~
--447--
semantic roles to various constituents in a source sentence as well as to choose their appropriate equivalents and sentential forms in the target language.
From the above considerations, a case structure is assigned to a sentence based on Hornby's
verb patterns.
Events of discourse are classified by categories of predicates.
Fig.l shows the upper part
of the categorical tree used here.
The categories used for describing case structures are, in
many cases, those appearing at the rightmost in
Fig.l.
Semantic roles of constituents are described
using case labels shown in Table i.
Table i
Case labels
PREDicate, AGent, OBJect, EXPERiencer, RECIPient,
SOurce, GOal, INSTRument, DEGree, COMPARison,
LOCation, TIME, RANGE, MANNer, ROLE, CAUSE,
RESULT, MEANS, PURPOSE, CONDition, MODal ( FORM,
TENSE, ASPECT, AFfirmation, MOOD, VOICE ), °..
By using several pairs of categories and case
-labels chosen from the above the main parts of
each event are schematically described and called
case-frames of events.
The first row of Table 2
is the main case-frame of the PTRANS event.
The m~in part of a case structure based on a
case-frame is transformed into a surface structure
using a verb which has a sufficient number of
Table 2
PREDPTRANS
Case-frame
assignment
AGTHINGS
of PTRANS action and
of verb patterns
OBJPHYS.OBJ
GOLOCAT U
PHYS.OBJ
PURPOSE
-ACT
ADVer
-bial
Adjunct
VP2B
VP2E
DEGQUANT
links to describe the main part and belongs to
an appropriate verb pattern.
Table 2 shows verb
patterns used for English description of PTRANS.
On the other hand, if a verb pattern is given, pairs of categories and case labels of dependants are almost determined every category of the
predicate verb as shown in Table 3. Hence, if
the verb patterns as well as the categories of a
verb are recorded in a word dictionary, the possible case structure can be retrieved at parsing
immediately.
Table 4 shows a part of pairs of
verb patterns and categories about ~take ~.
Example i shows several examples of case structures obtained by parsing with the aids of Table
4.
After determination of a case structure or a
dependency relation of a sentence, there still
remain several problems to be solved.
One of them is the choice of an appropriate
equivalent or a subcategory.
The word rtake~
with the verb pattern VP6A and the case structure
has fairly many Japanese equivalents.
However,
this kind of multi-vocal problems can be dissolved in many cases by looking up subcategories of
a few designated dependants involved in the case
structure and hence in advance by recording them
for each equivalent in the word dictionary as
shown in Table 4.
The other is the choice of an appropriate
Japanese postposition corresponding to a case
label and a category of a dependant of a verb.
Though a good correspondence generally holds between them, there are some exceptions.
For these
cases, the postposition is recorded at the item
of the associated verb in the dictionary and
picked up at parsing.
MANN
-ACT
Example
PResent
PARtici
-ple
SUBJect
VPI2A
VPI6A
Direct
Object
Indirect
Object
--
to-INFinitive
i
(i) VP6A : BODily ACTion
~He took bread. ~
(PRED-BOD.ACT:eat, MOD:(TENSE:past
~OICE:active), AG-HUM:he, OBJFOOD:bread)
tHe took a taxif
(PRED-BOD.ACT:get-on,
past, VOICE:active),
OBJ-VEHICLE:a-taxi)
MOD:(TENSE:
AG-HUM:he,
Table 3 Case structures of verb pattern VPI2A
IO
(2) VP6A : Mental TRANSfer
Cl took his speech. ~
(PRED-MTRANS:make-a-record-of,
MOD:(TENSE:past, VOICE:active),
AG-HUM:I, OBJ-EVENT:his-speech)
DO
VPI2A
SUBJ
PREDPTRANS
AGTHINGS
GOLOCAT U
PHYS. OBJ
OBJPHYS'0BJ
PREDPOSS'TRANS
AGHUM
RECIPHUM
OBJOBJECT
PREDMTRANS
AGHUM
EXPERHUM 0
MENT-SUBJ
OBJEVENT U
MENT.OBJ
(3) VPI5A : Physical TRANSfer
~I took the children to the park.
(PRED-PTRANS:go-leading, MOD:
(TENSE:past, VOICE:active),
AG-HUM:I, OBJ-HUM:the-children,
GO-LOCAT:the-park)
--448--
Table 4
Verb patterns
VP6A
VP22
A part of the item 'take' in the
word-dictionary
Categories
Meanings ( and the designated conditions )
BOD.ACT
i. get into one's hand ( OBJ-PHYS-OBJ )
2. eat
( OBJ-FOOD )
3. get on
( OBJ-VEHICLE )
PTRANS
I. go carrying
2. go leading
( OBJ-NON.LIVING
( OBJ-LIVING )
POSS'TRANS
i. receive
( OBJ-COMMODITY )
MTRANS
i. make a record of
:
( OBJ-MENT. OBJ
U EVENT )
PERCEP.ACT
1.
( OBJ-EVENT )
(4) VP22 : PERCEPtual ACTion
~I took her intelligent. ~
(PRED-PERCEP.ACT:suppose, MOD:(TENSE:past,
VOICE:active), EXPER-HUM:I, OBJ-EVENT:
(PRED-ATTR:intelligent, OBJ-HUM:she))
2.2 Optional cases
Adverbial phrases and clauses outside verb patterns constitute optional cases. Most of idiomatic phrase prepositions such as rwith respect to p
and many subordinate conjunctions such as Cwhen'
and Calthough * determine the case labels and the
Japanese postpositions of the following phrases
and clauses. On the other hand, many prepositional phrases which respectively have only one
prepositions such as c with ~ and Cfor' require the
information about frame of discourse for deter i
mination of the case label and the appropriate
Japanese postposition.
These information is the
categories of the object term of the phrase and
those of main verb of the governor and furthermore, in some cases, other information about
case structure of the verb pattern.
For example, an adverbial phrase consisting
of a prefixed preposition ~ in' and an object term
with category~PHYSical LOCation' can be assigned
a case label'LOC' or CGOal', but the appropriate
postposition and case label are determined by
referring to the semantic category of the main
verb.
The necessary information for determining
them are recorded each preposition and subordinate conjunction in the word dictionary.
2.3
Case structures of noun phrases and clauses
suppose
)
where t is the main term, ~ s are the dependants and K ~ - ~ is a pair of a case label and a
category.
The case structure only consisting of several
individual objects and prepositions are determined by referring to the categories of the
objects and their syntactic patterns linked with
the individual prepositions.
If a noun phrase contains some verbal nouns,
the case structure is constructed based on the
verbalized words of some of them.
Example 2
(i) Creceipt of his letter ~
C-EVENT: receive(PRED-POSS. TRANS: *,
OBJ-PHYS.OBJ:Ietter(OBJ: *,
POSS-HUM:his))
(2) t punctual arrival of trains'
C-EVENT: arrive(PRED-PTRANS: *, AG-VEHICLE:
trains, MANN-MODAL:punctual)
where C denotes a certain case for the outside
governor and the symbol * denotes the prefixed
term to the case frame containing it.
3.
Parsing
First, processing of negative expressions
and idioms are described.
They are processed in
a somewhat special manner.
3.1 Negative expressions
Negative expressions of English are fairly
different from those of Japanese at the points
where negative adjectives or adverbs of English
correspond to some negative modifiers and a
negative auxiliary verb in Japanese.
Hence, it
Case structures of noun phrases and clauses have
similar forms to those of sentences as follows;
t (Kr-Cl :t~ ,.. • ,K6-CL:t," • • ,K~-Cn:t~ ) (i)
--449
will be better to express the negative expression
of an English sentence in a language-free form at
the modal part of the case structure and to
generate the corresponding Japanese sentence from
that anew.
The types of NEGation are classified
to INTensified TOTal,TOTal and PARtial ones.
At parsing, the value of type is put in the
modal part of the case structure together with
the terms directly negated except the case when
the terms belong to the predicate part of the
sentence.
Example
~The problem was so difficult that he could
not solve it. ~
(PRED-ATTR:difficult, OBJ-MENT.OBJ:problem(OBJ
*, DET:def), DEG-QUAL:so(very), RESULT-EVENT:
(PRED-THINK.ACT:solve, MOD:(AF:TOT-NEG, MOOD:
can), AG-HUM:he, OBJ-THINGS:it))
3.3 Construction
of case structures
The rewriting rules used for parsing are described in a Chomsky-like form as follows~
3
(i) ~No student can solve the problem~
(PRED-THINK.ACT:solve, MOD:(AF:( INT. TOT.NEG,
student), MOOD:can), AG-HUM:student, OBJ
-MENT. OBJ:problem(OBJ:*, DET:def))
V l (K~-C, : tl , I K 2 - C 2 : ~2)
--~ V2 (K,-CI :tl ) V3 ( r~z- ~ Z :
J~Z ,VPi
)
(3)
V 3 (FKz- 6 2 : ~2' K3-C3 :ts ' VP£ )
--~ V% ( ] K ~ - ~ z : $2' VP{ ) V 5 (K3-C 3 : t 3 )
(4)
(2) ~Converses are not always true.'
(PRED-ATTR:true, MOD:(AF:(PAR'NEG, always)),
OBJ-MENT.OBJ:converses, FREQuency:
always)
Most of terms of modal cases are omitted here
and hereafter except important terms for simplicity.
3.2 Idiomatic expressions
For an efficient parsing, idiomatic expressions
are processed with some priority.
They are recorded near the heading of the leftmost wnrd
among multivocal constituents of the idiom in the
word dictionary.
If the idiom has a separated
form t l ~ t z as shown in Eq.(2),
t I s I •.. s~ t z
Example 4
(2)
the syntactic and semantic conditions on the
strings of words or phrases
sl, • . . , s ~
lying
between tl and t 2 are recorded together with
the partial case structure and the Japanese
equivalent of the idiom in the word dictionary
as follows;
so ~ that ~
(DEG-QUALity:so[ADVerb] very*, PRED-ATTR: ~f
[ADJective], RESULT(that[SUBORDInate CONJunction])-EVENT: ~ [ S E N T e n c e ] ) ,
where ~very*~denotes the Japanese word equivalent to the English word ~so ~.
When a constituent word. of an idiom is found
in a sentence at parsing, it is examined whether~
or not there exist the rest parts of the idiom
in the sentence by reading the sentence ahead
or by examining the partial case structure already constructed.
If there is, and if the
intermediate part
sl --. s ~ satisfies specified
conditions by parsing, the partial case structure
and the Japanese equivalent of the idiom are
added to those already constructed by referring
to the word dictionary.
Otherwise, ordinary
mode of parsing restarts from term t I
--450
where
V{ ( ~ =i ~ 5) denotes a non-terminal
symbol, ~ - ~ : ~ a sequent of several pai~s of
a case label and a category followed by a term,
and VPL a label of a verb pattern.
Eq.(3) represents the type of rewriting rules
of a subject and a predicate part, and Eq.(4)
that of a predicate part and a right dependent.
The parsing is done from left to right in a
bottom-up manner and case structures are constructed in the order of the predicate part, the
right part of a verb pattern of the predicate
part, the subject part and the optional adverbial parts.
This order is considered to be efficient for restricting possible construction of
case structures of many sentences of English
because the central structure is generally
constructed in this order.
At first, the partial case structure of the
predicate part is constructed.
If the main verb
is a constituent of an idiom, parsing is done in
a manner described in the preceding section.
Otherwise, all the case structures for the verb
patterns are constructed using the word dictionary and a table of case frames.
When a main term t6 with a category
CL
comes to be included in a partial case structure
S} (~ =1,2, ...,m) as shown in Fig.2, syntactic
and categorical consistency is checked.
If the consistency holds, the term with the
category
C~L is added to the partial case
structure
S~ with a designated case label K~L.
And if the case KiL is designated for dissolving
multi-Japanese equivalents of the main verb in
the case structure
S~ , appropriate Japanese
equivalents are extracted by subcategory matching.
Otherwise, if the category
C~& of the main
term t i does not match one of any partial case
structure
S~ ( ~=1,2, ..-,n), the category
C~L
is deleted.
Similarly, if a partial case structure requires a main term with a designated
semantic category and a designated syntactic
category or a position and cannot find the term,
the partial case structure is deleted.
( SUBJ )
(PRED )
tl
t+
t3
t2
KH
I
i Cln,l
I C~31
,
L-__4
r~-i
L -- _.J.
, Sm.t
I--_--4
Fig. 2
Construction
of case structures
Japanese sentences avoid sentential forms in
which non-living objects bring actions such as
causative and perceptive ones especially when
the actions directly affect human beings and
some events associated with them.
In Japanese,
these sentential forms are replaced by noncausative sentences or by resulted-state expressions using state-oriented verbs.
This problem
is well known as the non-living subject problems
and has been fairly well studied by many linguists. 5
It is shown here that the transformation of
the expressions can be processed in terms of
case structures in a systematic way.
First, the value of the voiee in the modal
case of such a sentence is set passive, because
in such a situation a passive form is generally
a little bit more acceptable than an active form
in Japanese.
Second, depending on the category
of the main verb and the agent, the agent case
is renamed to a more appropriate case so that a
more natural Japanese sentence is generated.
Third, if possible, the equivalent
of
the predicate part is modified into a more appropriate form such as state-oriented descriptions.
Some examples of this modification are shown
in Table 5.
In such a manner, the number of partial case
structures decreases or increases as a term is
added to partial case structures and, in many
cases, it reduces to unity at the end of parsing.
4. Case transformation
Some typical differences between English and
Japanese sentential forms do not require any
case transformation,
One of them is negative
expressions and processed as already mentioned
in section 3.1.
The others are oompound noun
expressions containing some verbal nouns which
are prefered to be verbalized in Japanese sentences.
However, these Japanese sentences are
directly generated from the case structure
obtained by parsing since the case structure of
a compound noun expression is constructed in the
same way as a sentence when it contains some
verbal nouns as mentioned in section 2.3.
Hence, the main differences which require
some case transformations are those as mentioned
as follows.
4.1 Case transformation for non-causative
state oriented descriptions
Table 5
Category of
predicate
Case
and
transformations
Instances
predicate
of
Case label
for agent
Modification
predicate
of
cause,make
CAUSE
ENABLE
enable
MEANS
INTRANS VERB
ENABLE
allow,permit
MEANS
CAUSE
REPL by'capable
verb *~
ENABLE
prevent
MEANS
CAUSE
REPL by ~not +
capable verb *~
PERCEPtual
ACTion
look
overlook
SOURCE
INTRANS VERB
+ capable verb
PERCEPtual
ACTion
show
MEANS
REPL by
Cunderstand,~
EMOTive
ACTion
surprise
please
CAUSE
INTRANS VERB
CAUSE
--451--
DELetion
respectively.
The main case transformations
as follows;
The third column of this table designates some
candidates of case labels to be renamed for an
agent•
The appropriate case label and postposition are determined by the category of the term
to be filled.
The fourth column designates the version
into which
the
equivalent of the predicate
part is to be modified.
The versions are classified into two kinds.
One of them is REPLacement
of the predicate part by a new intransitive verb•
The other is some modification of a passive
Japanese predicate part.
The latter is subdivided into DELetion of a causative verb, INTRANSitive VERBalizatio g and
addition of
the meaning Ccapable~ to it.
The version is coded and the code is recorded together with a new Japanese intransitive
verb for REPLacement in the word dictionary. In
'Fable 5, the words with a symbol * denote the
equivalent Written in Japanese•
At the execution of case transformation, the
routine designated by the code is called and
carries out the necessary processing.
Example
(i) (PRED-CAUSE:cause, AG-QUANT:weight(D~),
OBJ-EVENT:(PRED-PHYS.ACT:colIapse,
OBJ-PHYS. OBJ:shed(D2)))
---~(PRED-PHYS-ACT:colIapse, OBJ-PHYS.OBJ:
shed(Dz), CAUSE-QUANT:weight(DI))
where ~DI
:=OBJ-QUANT:*, DET:def,
POSS-PHYS.OBJ:snow,
D z :=OBJ-PHYS°OBJ:*, DET:def
(2) (PRED-ENABLE:alIow, MOD:(TENSE:past, AF:
TOT.NEG), AG-QUANT
:budget(D3) , OBJ-EVENT:
(PRED-ACT:start, AG-HUM:we, OBJ-MENT.ACT:
project(D#)))
--->(PRED-ACT:start, MOD:(TENSE:past, AF:
TOT-NEG, MOOD:can*), AG-HUM:we,
OBJ-MENT. ACT:projeet(D~), CAUSE-QUANT
:budget(D3))
where
5
By case transformation using Table 5, two
English sentences
(i) CThe weight of snow caused the shed to
collapse'
and
(2) 'Our limitted budget did not allow us to
start a new project'
are translated to Japanese sentences corresponding to
(f)'Owing to the weight of snow, the shed
collapsed'
and
(~)tOwing to our limitted budget, we could not
start a new project ~
Table 6
Miscellaneous
used here are
D 3 :=OBJ-QUANT
: *, POSS-HUM:we,
PRED-ATTR:Iimitted,
Di :=OBJ-MENT. ACT: *, DET:indef,
PRED-ATTR:new
Beside the above type of case transformations
@here are miscellaneous types of them.
A kind
of verbs such as ~bring ~ requires reference of
the category of a term in the object case as
well as the one about the recipient or goal
case.
A sentence containing a main verb such as
Cforce~ is transformed to a more preferable form
in Japanese which has a new manner case filled
with a term like ' inevitably ~ instead of the
main verb.
A sententlal form which includes the verb
~have ~ as a main verb is transformed to a more
case transformations
Change or
addition of
case
Modification
of predicate
Category of
predicate
Instances of
predicate
Referred
case category
PTRANS
bring
take
GOalPHYS. LOC
REPL by
MTRANS
bring
take
EXPER-HUMO
MENT. SUBJ
REPL by
~attain *~
CAUSE
force
compel
POSSession
have
~arrlve ~
ADDition of a
MANNer case
with
~inevitably* ~
POSS-HUM,
OBJ-HUM U
NATURalphenomenon
--452
-
CHANGE
from POSS
to EXHIBition
DELetion
REPL by
~exist*'
preferable form in Japanese even in the case the
POSSessor is a HUMan unless the expression is
like that "a living POSSessor has a PHYSical OBJect in his hand~
Some examples are shown in
Table 6.
ExamPle
respectively.
The first of the above translation
the case transformation;
no man
is done by
6
(PRED-PERCEP.ACT:awake, EXPER-HUM:he, RESULTEVENT:(PRED-PERCEP, ACT:find, EXPER-HUM:he,
OBJ-HUM:hlmself, LOC-PHYS°LOC:in-room(D )))
---> (PRED-PERCEP-ACT:find, EXPER-HUM:he,
OBJ-HUM:himself, LOC-PHYS.LOC:in-room
(D), TIME-INSTANT:when(PRED-PERCEP,ACT:
awake, EXPER-HUM:he))
By case transformation shown in Table 6, the
following three English sentences
(i) eA few minutes walk brought me the place ~
(2) ~The fact led him the conclusion'
(3) ~We had heavy snowfall last year ~
are translated
ponding to
into Japanese
sentences
corres-
where
(f) ~By walking for a few minutes, we arrived
at the place'
(~) ~From the fact, he attained the conclusion'
(~) 'There was heavy snowfall last year'
4.2 Case transformation
ordering
D :=OBJ-PHYS.LOC: *, DET:indef,
PRED-ATTR:strange.
The Other exceptional translations do not
have
definite
type, but are desirable for
readability of translated sentences when English sentences have some long adjective or adverbial subordinate clauses or phrases after
their rather short principal clause.
These
subordinate clauses have generally more concrete
and essential meaning than the principal clause.
In such cases, if translation is done in the
ordinary way so that the relation of subordinate
clauses to the principal clause remains unchanged, the generated Japanese sentence tends to
have a long essential subordinate part followed
by a short and rather introductory part of the
principal clause.
The Japanese sentences thus
obtained will often bring about difficulties in
immediate comprehension.
Furthermore, when a
part of subordinate clauses is referred in the
next sentence, the immediate identification of
the anaphora will not be so easy owing to
increase of distance from the referring part as
shown in Fig. 3.
In such cases a continuative translation is
more preferable. 6 It assigns a location succeeding to the principal clause for an equivalent
of the subordinate clause.
The subordinate clauses are classified to adverbial clauses and
adjective ones.
In the former case, the subordinate clause
is qualified as a sentence or a coordinate clause in a continuative translation.
For a coordinate clause, the coordinate conjunction is
preceded which is determined by the ease label
of the adverbial clause and more precisely by
the preposition or the subordinate conjunction.
In the latter case, syntactic roles of a principal clause and a relative clause are reversed
through a modified term as follows;
respectively.
In sentence (i), the agent with the category
PTRANS action is verbalized in construction of
the case structure, and renamed as the case
CMEANS' by the case transformation.
for target-clause
This section describes a case transformation by
which the order of clauses of a target sentence
corresponds to that of a source sentence to some
extent in the locative or temporal sense.
In general, an English sentence is translated
into a Japanese sentence so that dependency
relations in surface structure such as those of
subordinate clauses to the principal clause do
not change so much for preserving the stream of
the main subjects included in successive English
sentences.
However, there are several exceptions.
One
of them has a comparatively definite type in
sentential forms as well as in translation.
A
certain kind of English sentences do not correspond t o n a t u r a l Japanese sentences unless the
relation of a subordinate clause to the principal
one
is reversed.
For example, if a
resultant state is contained as a dependent in
an English sentence which describes an action or
a state, each of them is generally described in
Japanese as a dependent in a sentence which
describes the result as shown in Example 7.
Example
and
~Because the problem was so difficult,
could solve it'
7
Two English sentences
s
%
(K I :t I ,Kz:t 2, • • .,Ka:t~ (K I :sl , • • • ,K£: ~.,
I
. . . .
K~:s~ ))
tHe awoke to find himself in a strange room'
and
~The problem was so difficult that no man could
solve it ~
--~ (KL:t ~ (K~:tl, Kz:tz,...,,
I
=
KI:sI
,
• • , K~:s~
K~: *
)
)~
5)
where the double-underlined case means that a
thematic fronting and addition of a certain
thematic postposition is done for the underlined case in generation of a Japanese sentence
are translated to Japanese sentences corresponding to
~When he awoke, he found himself in a strange
room'
--453--
referred
I
l PRE0 I
principal
clause
(a)
subordinate
clause
the
next
sentence
a source sentence
referred
I
parts of
principal
clause
subordinate
clause
(b)
Fig.
from the transformed
3
principal
clause
the next sentence
a Japanese sentence
Order of subordinate
and principal
clauses
case structure.
5.
Example
Conclusion
8
The ease structures obtained by parsing or
the transformed case structure are expanded in
an appropriate term-order by a Japanese grammar
under various control of the involved parameters.
Some experimental results show that this
approach is effective to dissolve multi-syntactic and semantic category problems of words and
phrases and efficient to transform case structures.
From the view point of more precise and
multi-lingual translation, it is desirable that
more precise, detailed and standardized definition is established for case structures and
hierarchic category systems and also their codes
are attached to some word dictionaries.
It will
not be impossible as far as mechanical translation of technical papers is concerned.
Two English sentences
'Science deals with sense impressions which are
similar to make universal agreement possible'
and
'That all men are all equal describes a proposition to which no sane human being has ever been
given his assent'
are translated into Japanese sentences corresponding to
'Sense impressions which science deals with are
similar to make universal agreement possible'
and
'To a proposition which describes that all men
are all equal no sane human being has ever been
given his assent'
respectively.
A sentence which contains a kind of appositions is also transformed as follows;
References
( K 1 : t l , . , . , KL:it, • • . , Kk:tk,
K~:that(K~:sl, . .
, K~:sz ))
---> (PRED:that(K~:st, . . . , K~:sb ),
OBJ:it(K I :t I ,...,KL:*, • • , K~:t~))
where
K~
Example
is an apposition
case to a case
i. Wilks,Y.~An artificial intelligence approach
to machine translation', Schank and Colby
(eds.), Computer models of thought and language, San Francisco, Freeman,p.l14,(1973).
2. Vauquois,B.,'Aspect of mechanical translation
in 1979', GETA,Unlv.Grenoble, (1979).
3. Hornby,A.S.,'Guide to patterns and usage in
English',second edition,London, Oxford University Press, (1975).
4. Bruce,B.,'Case systems for natural language',
Artificial Intelligence,Vol.6,p.327,(1975).
5. Kunihiro,T.,'Structural semantics',
Sansei-do,(1976), (written in Japanese).
6. Bekku,S.,'Study of translation',
Yashio-shuppan-sha,(1976),(written
in
Japanese).
(6)
KL.
9
An English sentence
'We should make it clear that they lead the
same conclusion'
is translated to a Japanese sentence corresponding to
'That we should make clear is that they lead
the same conclusion'.
--454--